June 7, 2012 : NGK explains the causes of the fire incident and countermeasures

From June 2012 : upgrade of existing batteries facilities

October 2012 (?) : batteries production resumed

Small cause, big effects

After months of silence, NGK finally communicates on June 7th, 2012, about the NAS battery fire incident. The cause: a single faulty cell. One of 15,360 cells composing a 2 MW block. The solution: safety enhancement. No need for design change. Big incident, easy solution.

Countermeasures

Since June 2012, existing NAS batteries facilities are, one after the other, upgraded to safety enhancement, by implementing following measures to prevent the spread of fire in modular batteries :

Fuses between battery cells

Insulation boards between blocks in battery modules

Anti-fire boards above and below battery modules.

The two first measures requires about 6000 battery modules from 174 locations in Japan, France, Germany, UAE, UK and USA to be collected in NGK facilities in Japan and then shipped back.

Along with additional safety measures (improved fire monitoring system, installation of fire extinguishers and fire-prevention equipment), as well as facilities organisation improvement (setup of a fire-fighting structure on site and of a fire evacuation route, with guidance system).

Production of new batteries

New batteries would be produced at the earliest in October 2012. Business development perspectives are nevertheless maintained, mainly because NGK niche market is waiting for their batteries. unless GE’s Durathon shows up…